(1)a⊥b=> a.b=0(cos(3x/2),sin(3x/2).(cos(x/2),-sin(x/2))=0cos(3x/2)cos(x/2)-sin(3x/2)sin(x/2)=0cos2x=02x = nπ+π/2x = nπ/2 + π/4 n=0,1,2,...x的值的集合 = { x | x= nπ/2 + π/4,n=0,1,2,.}(2)a-c = ( ...